uop5 manual - issue 18

8/10/2019 UOP5 Manual - Issue 18

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INSTRUCTION MANUAL

UOP5

LIQUID/LIQUID EXTRACTION UNIT

UOP5



ARMFIELD LIMITED

OPERATING INSTRUCTIONS AND EXPERIMENTS

UOP5 - LIQUID/LIQUID EXTRACTION UNIT

Page No.

SAFETY IN THE USE OF EQUIPMENT SUPPLIED BY ARMFIELD 1

INTRODUCTION 6

RECEIPT OF EQUIPMENT 7

DESCRIPTION 8

ASSEMBLY 15

CONNECTION TO SERVICES 17

COMMISSIONING 19

ROUTINE MAINTENANCE 22

INDEX TO EXPERIMENTS 26

SOLVENT/SOLUTE SYSTEMS FOR USE WITH UOP5 ii

CALIBRATING THE SOLVENT METERING PUMP iii

GENERAL SAFETY RULES a

ELECTRICAL DIAGRAM CDM22529 Appendix



SAFETY IN THE USE OF EQUIPMENT SUPPLIED BY ARMFIELD

Before proceeding to install, commission or operate the equipment describedin this instruction manual we wish to alert you to potential hazards so thatthey may be avoided.

Although designed for safe operation, any laboratory equipment may involveprocesses or procedures which are potentially hazardous. The major potentialhazards associated with this particular equipment are listed below.

INJURY THROUGH MISUSE

INJURY FROM ELECTRIC SHOCK

INJURY FROM INCORRECT HANDLING

POISONING FROM TOXIC MATERIALS

INJURY FROM CORROSIVE LIQUIDS

RISK OF INFECTION THROUGH LACK OF CLEANLINESS

DAMAGE TO CLOTHING

Accidents can be avoided provided that equipment is regularly maintained and staff and students are made aware of potential hazards. A list of generalsafety rules is included in this manual, to assist staff and students in thisregard. The list is not intended to be fully comprehensive but for guidanceonly.

Please refer to the notes overleaf regarding the Control of SubstancesHazardous to Health Regulations.



The COSHH Regulations

The Control of Substances Hazardous to Health Regulations (1988)

The COSHH regulations impose a duty on employers to protect employees and others

from substances used at work which may be hazardous to health. The regulations

require you to make an assessment of all operations which are liable to expose any

person to hazardous solids, liquids, dusts, vapours, gases or micro-organisms. You are

also required to introduce suitable procedures for handling these substances and keep

appropriate records.

Since the equipment supplied by Armfield Limited may involve the use of substances

which can be hazardous (for example, cleaning fluids used for maintenance or

chemicals used for particular demonstrations) it is essential that the laboratory

supervisor or some other person in authority is responsible for implementing the

COSHH regulations.

Part of the above regulations are to ensure that the relevant Health and Safety Data

Sheets are available for all hazardous substances used in the laboratory. Any person

using a hazardous substance must be informed of the following:

Physical data about the substance

Any hazard from fire or explosion

Any hazard to health

Appropriate First Aid treatment

Any hazard from reaction with other substances

How to clean/dispose of spillage

Appropriate protective measures

Appropriate storage and handling

Although these regulations may not be applicable in your country, it is strongly

recommended that a similar approach is adopted for the protection of the students

operating the equipment. Local regulations must also be considered.

Water-Borne Infections

The equipment described in this instruction manual involves the use of water which

under certain conditions can create a health hazard due to infection by harmful micro-

organisms.



Under the COSHH regulations, the following precautions must be observed:-

Any water contained within the product must not be allowed to stagnate, i.e. the water

must be changed regularly.

Any rust, sludge, scale or algae on which micro-organisms can feed must be removed

regularly, i.e. the equipment must be cleaned regularly.

Where practicable the water should be maintained at a temperature below 20°C or

above 45°C. If this is not practicable then the water should be disinfected if it is safe

and appropriate to do so. Note that other hazards may exist in the handling of biocides

used to disinfect the water.

A scheme should be prepared for preventing or controlling the risk incorporating all of

the actions listed above.

Further details on preventing infection are contained in the publication “The Control

of Legionellosis including Legionnaires Disease” - Health and Safety Series booklet

HS (G) 70.



USE OF A RESIDUAL CURRENT DEVICE FOR ELECTRICAL SAFETY

The equipment described in this Instruction Manual operates from a mains voltage

electrical supply. The equipment is designed and manufactured in accordance with

appropriate regulations relating to the use of electricity. Similarly, it is assumed that

regulations applying to the operation of electrical equipment are observed by the end

user.

However, it is recommended that a Residual Current Device (RCD) alternatively

called an Earth Leakage Circuit Breaker (ELCB) be fitted to this equipment. If

through misuse or accident the equipment becomes electrically dangerous, an RCD

will switch off the electrical supply and reduce the severity of any electric shock

received by an operator to a level which, under normal circumstances, will not cause

injury to that person.

If the electrical supply to the laboratory already incorporates an RCD, then the device

supplied with the equipment need not be used. If the electrical supply does not

incorporate such protection then the loose RCD supplied by Armfield Ltd should be

fitted by a competent electrician either in the supply to the laboratory or in the supply

to the individual item of equipment. Drawing Number BM20491 gives full

installation instructions.

Note: If any doubt exists whether the electrical supply incorporates a device then the

RCD supplied should be fitted.

At least once each month, check that the RCD is operating correctly by pressing the

TEST button. The circuit breaker MUST trip when the button is pressed. Failure to

trip means that the operator is not protected and the equipment must be checked andrepaired by a competent electrician before it is used.



1 3

2 4

Clip

To equipment

Off position

L i v e ( B r o w

n )

N e u t r a l ( B l

u e )

E a r t h ( G r e e n / Y e l l o w )

Remove 130mm outer sheath, cutLive (brown) & Neutral (blue)

NOT EARTH (green/yellow)

from

BM20491

1.

Ensure equipment is disconnected from

electrical supply

2. Locate suitable position for RCD on oradjacent to equipment

3. Remove cover from mounting base

4. Position base, mark off, drill through 2holes

5. Fix base at location using suitable

screws6. Fix RCD to base

7. Remove 130mm of outer sheath of

cable in line with RCD8. Cut live and neutral, connect to RCD.

Do not cut earth.

9. Fit cover to base and RCD

10. Reconnect main power supply

11. Switch on RCD

L i v e

N e u t r a l

E a r t h



INTRODUCTION

Many processes in chemical engineering require the separation of one or more of the

components of a liquid mixture by treating the mixture with an immiscible solvent in

which these components are preferentially soluble. In some cases purification of a

liquid may be the function of the process, in others the extraction of a dissolved

component for subsequent processing may be the important aspect. An example of the

former is the preparation of pure organic liquids from products of the oil industry.

Liquid/liquid extractions may also be used as energy-saving processes by, for

example, eliminating distillation stages. It is possible, of course that the substance of

interest may be heat-sensitive anyway and that distillation is accordingly an

unacceptable process.

The rate at which a soluble component is transferred from one solvent to another will

be dependent, amongst other things on the area of the interface between the two

immiscible liquids. Therefore it is very advantageous for this interface to be formed

by droplets and films, the situation being analogous to that existing in packed

distillation columns.

The Armfield Liquid/Liquid Extraction Unit takes the form of a vertically-orientedpacked column which may be operated either, by filling the column with water and

allowing a solvent to flow down the column over the packing, or filling the column

with solvent and allowing water to flow up the column over the packing. In either case

the process is continuous, both liquids being pumped into the column. Sensing

electrodes at the top and bottom of the column determine whether the column is filled

with water or with solvent. This is achieved by sensing and maintaining the position

of the water level at the appropriate height. A solenoid valve controlling the flow of

solvent under gravity from the column is operated by the sensing electrode system.

A distillation unit with a fractionating column is included to allow the reclamation of

solvent where appropriate.



RECEIPT OF EQUIPMENT

1. SALES IN THE UNITED KINGDOM

The apparatus should be carefully unpacked and the components checked against the

Advice Note. A copy of the Advice Note is supplied with this instruction manual for

reference.

Any omissions or breakages should be notified to Armfield Ltd within three days of

receipt.

2. SALES OVERSEAS

The apparatus should be carefully unpacked and the components checked against the

Advice Note. A copy of the Advice Note is supplied with this instruction manual for

reference.

Any omissions or breakages should be notified immediately to the Insurance Agent

stated on the Insurance Certificate if the goods were insured by Armfield Ltd.

Your own insurers should be notified immediately if insurance was arranged by

yourselves.



DESCRIPTION

All numerical references relate to the Equipment Diagram on page 11 and the

Component System Diagram on page 12 and in the experimental section of this

manual.

All letter coded references relate to the Control and Instrumentation System Diagram

on page 13 and in the experimental section of this manual.

The equipment is mounted in a floor-standing, welded steel framework (8) fitted with

adjustable feet (12). The frame contains an extra cross-member (9) at the front and a

similar one at the rear to allow the use of a fork-lift truck.

The glass liquid/liquid extraction column (19a & 19b) is fitted with enlarged end

sections (14), (25), which are closed by stainless steel plates (13), (26), the lower one

being bolted to the framework and supporting the column. The four sections of the

column proper and the two end plates are all fastened together with flanges (15), the

joints between the sections being sealed with moulded PTFE gaskets. The column is

filled with Raschig rings which are supported on a perforated stainless steel plate (16)

fitted between the bottom enlarged portion and the lower section of the column.

Water for the column is stored in the supply tank (37) (L2) from where it is pumped

by the centrifugal pump (4), through an air bleed valve (5) (V3), a flow control valve

(23) (C1) and a flowmeter (24) (F1) to an injector (28) mounted in the baseplate and

with its exit about 150mm above the plate. Water leaves the top of the column

through a pipe, and is collected in a polythene tank (40) (L1).

All storage tanks for solvent are constructed in stainless steel. The organic solventsupply tank (3) (L5) provides the feed for the solvent metering pump (43) (F2), the

pumping rate of which is varied by a stroke adjustment knob (1) and indicated by a

dial calibrated from 1 – 10 where 10 is the maximum flow (nominally 380ml/min at

50Hz). Pumped solvent enters the top of the column via an injector similar to that

fitted at the base for the water (28). A sampling and drain cock (2) (V6) is fitted in the

solvent feed line.

NOTE: The stroke adjustment knob on the metering pump must only beadjusted when the pump is running. The smaller clamping knob must be

unscrewed before making an adjustment then tightened again when the

adjustment knob is in the required position (scale is calibrated 1 – 10).

A 3-way valve (V8) at the discharge of the solvent pump allows the flow from the



Solvent from the base of the column is returned under gravity to the receiver vessel

(36) (L3) via a pipeline (27) which is also fitted with a solenoid valve (6) (C3) and a

sampling cock (V9).

The level of the water/solvent interface in the column is determined by the operation

of the solenoid valve (6) (C3) in the solvent outlet pipeline. The operation of this

valve is controlled by water-sensing electrodes, one set fitted to the top plate (31) and

another set to the bottom plate (11). A switch (S2) on the system control panel (34)

(see also diagram of the panel) selects the electrodes in use and hence determines

whether the interface is at the top or bottom of the column. Each electrode set consists

of three stainless steel electrodes, a bare earth electrode to make continuous contact

with the water and two others of different lengths insulated to points 5mm from theirends. These insulated electrodes are set to heights differing by 5mm which produces a

liquid level differential of 5mm.

The purpose of this arrangement is to avoid frequent opening and closing of the

solenoid valve which would occur with a simple single-electrode system. The

electrical sensing system operates at a low AC voltage and the conduction current

through the water is small, the latter being translated into a solenoid-operating voltage

by a plug-in module behind the control panel.

The receiver vessel (36) (L3) may be connected to the solvent supply vessel via a

pipeline and a valve (38) (V4). Thus, liquid which has passed through the column

once may be treated again in a batch wise fashion or the valve (38) (V4) may be left

open during the extraction to provide a closed circuit, the solvent then being re-

circulated continuously.

The distillation column boiler (20) (L6), mounted behind the extraction column, isfitted at such a height that liquid may be drained into it from the upper of the three

solvent tanks and can be drained from it into the lowest tank. The valve (18) (V7)

controls the release of solvent into the boiler. Like pipework, valves and fittings, the

boiler is constructed in stainless steel. Heating is by means of two 500W cartridge

elements inserted at the base of the boiler and boiler temperature is indicated on a

thermometer in the side. The boiler lid is perforated where the distillation column is

fitted (35) and three blind tapped holes around this area accept bolts fixing the column

flange to the boiler.

The column proper is made up of a glass section (22) containing four sieve plates. The

glass reflux divider (33) bolts to the column top and to the stainless steel condenser

above it with bolts and flanges and all the sections are sealed together with moulded

PTFE gaskets.



Condensate from the reflux divider flows under gravity into the middle solvent tank

(39 (L4) via the flow control valve (17) (C2) which thus determines the reflux ratio.

The contents of the middle tank (39) (L4) can be drained into the solvent supply tank

by opening the valve (41) (V5) between the two.

The three solvent tanks (36) (L3), (39) (L4), (3) (L5) are vented to atmosphere through

a vent pipe which is inserted into the top of the condenser. Solvent levels in the tanks

and boiler are indicated with glass sight tubes protected by clear polyethylene sleeves.

Control of the equipment is simplified with a system diagram panel (34) shown in

detail on page 12. The complete solvent/water flow system is shown with electricalcontrols at the appropriate points on the diagram. These are mains on/off switch (S1),

water pump on/off switch (S3), solvent pump on/off switch (S4), boiler heater switch

(S5) and power regulator (R1), electrode changeover switch (S2), and solenoid valve

'open' indicator light. The four mains supply switches are self-illuminating in the 'on'

position. A mains transformer (42) is supplied when the electrical supply is 120V,

60Hz A.C.



INSTALLATION REQUIREMENTS

ELECTROMAGNETIC COMPATIBILITY

This apparatus is classified as Education and Training Equipment under the

Electromagnetic Compatibility (Amendment) Regulations 1994. Use of the apparatus

outside the classroom, laboratory or similar such place invalidates conformity with the

protection requirements of the Electromagnetic Compatibility Directive (89/336/EEC)

and could lead to prosecution.

FACILITIES REQUIRED

The equipment is floor mounted and requires a level area that is capable of supporting

the weight of the equipment.

A single phase A.C. mains electricity supply is required for connection to the

equipment via the attached cable. The mains plug fitted will depend on the version

supplied to suit the local electrical supply.

Three versions of the UOP5 are available: -

UOP5-A 220/240V/1ph/50Hz, fused @ 10 Amps – mains lead

fitted with 2 pin Shuko plug (European) with 3 pin

adaptor (UK)

UOP5-B 110/120V/1ph/60Hz, fused @ 15 Amps – supplied with

separate transformer fitted with NEMA 5-15P plug

(125V USA)

UOP5-G 220V/1ph/60Hz, fused @ 10 Amps – mains lead fitted

with NEMA 6-15P plug (250V USA)

Note: Version UOP5-B is supplied with a loose transformer to step-up the 120V

supply to 230V to suit the equipment. The transformer should be sited adjacent to the

120V mains outlet socket in the laboratory, in a dry location. The mains lead from the

UOP5 is simply plugged into the 230V 3 pin outlet socket on the front of the

transformer.

A cooling water supply is required for the condenser of up to 5 litres/minute at 1 barg

pressure. The water supply should be connected using 12.7 mm (0.5”) I.D. reinforced

flexible hose (not supplied). The water exiting the condenser should be led to a

suitable drain using similar hose.



ASSEMBLY

All numerical references relate to the diagram on page 11.

All alpha numeric references relate to the diagram on page 13

1. Locate the framework in the desired location following the recommendations

in 'Installation Requirements'. Care should be exercised if using a fork-lift or

other lifting tackle to install the equipment as pipework and components are

exposed at the base of the equipment.

2. Disconnect all pipework connections to the top plate (26) on the extractioncolumn. Disconnect the three level electrodes from the top plate noting relative

positions.

3. Remove the top extraction column supporting bracket. Remove the top plate

from the extraction column by removing the six nuts and bolts.

4. Three-quarters fill the column with clean water using a bucket or hose pipe.

5. Load 0.1 litres of 15mm diameter Raschig rings followed by 2.4 litres of

10mm Raschig rings into the column. Until the level of rings reaches the top

white P.T.F.E. gasket situated between the thin and enlarged sections of the

column.

6. Drain all water from the extraction column by opening the drain cock V11 in

the base of the column

7. Replace the top plate on the extraction column. Ensure the sealing gasket is

correctly fitted. Tighten the six nuts and bolts. Replace the column supporting

bracket.

8. Replace the electrodes, connecting wires and pipework connections (Details

about the connections to the electrodes are included in the Routine

Maintenance section of this instruction manual).

9. Connect the 3 way stainless steel valve V8 (complete with pipework and

sample valve (V13) between the discharge connection on the solvent pump

and the pipework to the injector on the top plate of the extraction column.

10. Attach the pre-bent vent pipe to the spare stud coupling located on the top



12. Carefully tighten all couplings on the extraction column and distillation

column, applying equal tension to each bolt.

To avoid distorting the P.T.F.E. sealing ring between the couplings, the topand especially the base of the column - do not over-tighten sealing bolts and

washers.

13. Locate the glass thermometer (T2) (30) in the branch of the reflux divider.

Tighten the nylon union.

NOTE: Ensure that behind the silicone seal on the solvent side a P.T.F.E.

washer is fitted to protect the silicone against the solvent.

14. Remove the oil filler plug from the top of the gearbox on the solvent pump and

fill the gearbox with the oil supplied (General Gear Lubricant type 85W140).

Check that the level is coincident with the mark on the dip stick then replace

the filler plug and dip stick.



CONNECTION TO SERVICES

ELECTRICAL SUPPLY FOR VERSION UOP5-A:

This version of the equipment requires connection to a single phase, fused electrical

supply. The standard electrical supply for this equipment is 230V, 50Hz. Check that

the voltage and frequency of the electrical supply agree with the label attached to the

supply cable on the equipment.

The Shuko 2 pin plug can be connected directly to European style mains outlet

sockets. The 3 pin adaptor should be fitted to the Shuko plug when connecting the

equipment to 3 pin UK style sockets.

When installing the equipment it will not be necessary for an electrician to terminate

any bare electrical connections but for information the supply cable and electrical

wiring on the UOP5 uses the following convention:-

GREEN/YELLOW - EARTH

BROWN - LIVE (HOT)

BLUE - NEUTRAL

Fuse Rating - 10 AMP

ELECTRICAL SUPPLY FOR VERSION UOP5-B:

The equipment requires connection to a single phase, fused electrical supply. The

standard electrical supply for this equipment is 120V, 60Hz. Check that the voltage

and frequency of the electrical supply agree with the label attached to the supply cable

on the equipment.

This version of the UOP5 is supplied with a loose transformer to step-up the 120Vsupply to 230V to suit the equipment. The transformer should be located adjacent to

the 120V mains outlet socket in the laboratory, in a dry location. The mains lead from

the UOP5 is simply plugged into the 230V outlet socket on the front of the

transformer. The NEMA 5-15P plug on the mains input lead to the transformer should

be connected to a 120V mains outlet socket.

When installing the equipment it will not be necessary for an electrician to terminate

any bare electrical connections but for information the supply cable and electricalwiring on the UOP5 uses the following convention:-


BROWN - LIVE (HOT)

BLUE - NEUTRAL



The NEMA 6-15P plug on the mains input lead to the equipment should be connected

to a 220V mains outlet socket.

When installing the equipment it will not be necessary for an electrician to terminateany bare electrical connections but for information the supply cable and electrical

wiring on the UOP5 uses the following convention:-


BROWN - LIVE (HOT)

BLUE - NEUTRAL

Fuse Rating - 10 AMP

COLD WATER

The condenser inlet pipe is situated at the base of the condenser and terminates on the

distillation column support bracket in a hose nozzle. Connect the hose nozzle to a

supply of cold water (5 litres/min at 1 barg) using 12.7mm (0.5”) I.D. flexible hose

(not supplied). Secure the connections using pipe clips.

DRAIN (WARM WATER)

The condenser drain pipe is situated at the top of the condenser and terminates

adjacent to the cold water inlet pipe in a hose nozzle. Connect the hose nozzle to a

suitable drain using 12.7 mm (0.5”) I.D. flexible tubing (not supplied). Secure the

connections using pipe clips.

VENT SYSTEM

All vessels and pipework are connected to a common vent point at the top of the

condenser, above the distillation column. This ensures that no pressure can build-up in

the system in the event of condenser failure such as failure of the cooling water

supply. Because solvent vapour can escape from the common vent point this must be

connected to a suitable extraction system (not supplied) or connected via a pipe (not

supplied) to the outside of the building.



8. Close drain valve (V11) in base of column. Open control valve C1 and adjust

to give full scale reading on flowmeter F1. C3 will close again when the water

level reaches the short electrode then the column will gradually fill. Leave the

electrode switch in the down position. Check C3 is still closed (light off). Waitfor water level to reach the top plate i.e. column completely full. Make sure

water flows from the top of the column to the polythene storage tank (L1).

9. Switch S2 to top electrodes position. Check C3 remains closed. Close the

flowmeter control valve C1. Open the drain valve V11 at the base of the

column and allow water to drain until the water level falls below the long

electrode. Check valve C3 opens (light on). Water will drain into tank L3 until

level in column equals level in tank L3.

10. Check pipework and column for leaks.

11. Switch off water pump (switch S3). Drain all remaining water from column

through drain valve V11 in base of column.

12. Fill vessel L3 with tap water through top filler. Check sight gauge on L3

operates.

13. Half fill vessel L4 with tap water through top filler. Check sight gauge on L4

operates.

14. Open valve V7. Allow boiler L6 to 1/3rd fill with water. Close valve V7.

Check sight gauge on L6 operates.

15. Open valve V4. Allow vessel L5 to fill with water - allow L3 to drain. Closevalve V4. Check sight gauge on L5 operates.

16. Set calibration valve V8 to the column position, open sample valve V13 at the

solvent pump discharge and place a suitable container beneath the valve to

allow the water which will discharge to be collected. Switch on the solvent

pump (switch S4) then, with the pump running, unscrew the clamp and set the

stroke adjuster to 100% (10 on F2) then tighten the clamp screw.

When water flows from sample valve V13 close valve V13 and check that

water is delivered to top injector inside extraction column. Locate a suitable

container beneath outlet from the calibration valve V8. Set calibration valve

V8 to calibrate position and check that water flows from valve V8. With

solvent pump still running unscrew clamp and set stroke adjuster to 50% (5 on



NOTE: The solvent metering pump needs to be calibrated using valve V8

before experiments can take place. This procedure is described in the

experimental section of this manual (page iii).

17. Connect cooling water to lower connection on condenser. Connect top

connection on condenser to drain.

18. Turn on cooling water supply. Check flow of water to drain. Check for leaks.

19. Set power control R1 to minimum (fully anti-clockwise). Switch on heating

elements (switch S5). Rotate power control R1 to maximum (fully clockwise).

Check temperature of water increases (Thermometer T1). Check boiler forleaks. Allow water to boil. When condensate collects in reflux divide open

control valve C2. Check water flows from reflux divider to vessel L4.

20. Set power control R1 to minimum (fully anti-clockwise) then drain the boiler

by opening valve V10. When the level falls below the level switch power

should be disconnected (S5 not illuminated). Switch off the boiler (S5).

21. Disconnect the electrical supply, turn off cooling water and drain all waterfrom the equipment.



ROUTINE MAINTENANCE

To preserve the life and efficient operation of the equipment it is important that theequipment is properly maintained. Regular servicing/maintenance of the equipment is

the responsibility of the end user and must be performed by qualified personnel who

understand the operation of the equipment.

In addition to regular maintenance the following notes should be observed:-

1. Disconnect the equipment from the electrical supply when the equipment is

not in use.

2. Drain all solvent from the equipment after use.

3. After using or creating contaminated solvent, flush the system through with

clean solvent before finally draining.

4. Periodically clean the exposed metal surfaces of the level electrodes at the top

and bottom of the extraction column. If the electrodes are disconnected fromthe connecting leads ensure that they are re-connected correctly as follows:

TOP Electrodes

20mm electrode - cable number 29 (Green/yellow Earth lead)

45mm electrode - cable number 28


BOTTOM Electrodes



60mm electrode - cable number 29 (Green/yellow Earth lead)

5. To avoid distorting P.T.F.E. sealing ring between the couplings, the top andespecially the base of the column - do not over-tighten sealing bolts and

washers.

6. Check the level of the oil in the gearbox of the solvent pump. The correct level

is indicated by a dip stick on top of the gearbox. The gearbox can be topped up



MCB1 Mains Supply 10 Amp (Top)

MCB2 Instrumentation 3 Amp

MCB3 Water Pump 5 Amp

MCB4 Solvent Metering Pump 5 Amp

MCB5 Distillation Column Heater 5 Amp (Bottom)



USE OF LEKSOL

Water and certain other contaminants can over time, cause the breakdown of the

solvent molecule to form free acid that can have a serious effect on components of

UOP5. The solvent stabilization package present within the solvent formulation

protects against the generation of free acid by acting as acid acceptors. It is important

therefore to ensure that the level of stabilizer present within the solvent is sufficient to

meet these demands. The stabilizer content present can be determined by the addition

of a known amount of standard hydrochlorination reagent.

Test Procedure:

Method 1 – TitrationAll reagents should be reagent grade, ACS specification or equivalent.

Sodium hydroxide – 0.1N

Hydrochlorination reagent – standardised 0.1N hydrochloric acid in anhydrous

propan-2-ol. Make solution by adding 8.50ml of 37% HCl to 500ml of anhydrous

propan-2-ol and then diluting with further anhydrous propan-2-ol to 1 litre in a

graduated flask.

Propan-2-ol

Bromophenol Blue indicator – 0.1% w/wPipette – 10ml and 25ml

Erlenmeyer flask, glass stoppered, 125ml or 250ml

Burette, 50ml, calibrated to 0.1ml

Procedure:

1. Pipette 10ml of the solvent sample into a stoppered flask

2. Pipette 25ml of reagent and 25ml of dry propan-2-ol into the flask

3. Stopper the flask and shake the mixture thoroughly to assist the hydrochlorination.

4.

Allow to stand for 10 minutes5. Add 5 drops of indicator then titrate to a light purple end-point using standardised

0.1N NaOH.

6. Titrate a blank containing only 25ml of hydrochlorination reagent and 25ml of

propan-2-ol.

Note: Ensure that the flask and pipette are dry before proceeding with the test. If

turbidity or phase separation occurs then add a small amount of propan-2-ol.

CalculationReport total acid acceptance as weight percent equivalent NaOH which is calculated

as follows:

( )

321

4tan%

×

××−=

S

N A Bce Accep Acid



Requires the test kit supplied by Conservation Resources (details available via

http://www.conservationresources.com ).

Procedure

1.

Find the value of B-A using the test kit and the instructions for its use presented in

the method set out in the Technical Information Sheet.

2. Convert the number of drops (B-A) to an acid acceptance value (%) by dividing

the result by 200.

Compare the acid acceptance value determined by Method 1 or 2 to the ranges quoted

in Table 1 below.

No of drops = B-A Acid Acceptance value Action Required0 to 7 < 0.04% Dangerously low – replace with

new Leksol

8 to 16 0.4 to 0.08% Low, top up with fresh solvent or

add stabiliser

17 to 60 0.08 to 0.40% Normal range

60 and over > 0.40% New Leksol, no action required

REGENERATION OF LEKSOL

The solvent may be recovered by either of two procedures.

Procedure 1

Spent Leksol is recovered using the UOP5 distillation column. The recovered solvent

requires stabiliser to be added to prevent solvent breakdown and acid formation. The

stabiliser is called Lekstab and is available from Conservation Resources

(http://www.conservationresources.com). The stabiliser should be added to give a

final concentration of 0.40%. The stabiliser in its neat form is particularly toxic andshould be handled with care.

Procedure 2

Following distillation and recovery of the solvent the stabiliser is replaced by blending

virgin solvent with recovered solvent at a minimum ratio of 4 parts virgin solvent to 1

part recovered solvent. There will be a slight drop in the acceptance value compared

to new material but this will not compromise the effectiveness of the solvent.



UOP5 - LIQUID/LIQUID EXTRACTION UNIT

INDEX TO EXPERIMENTS

Experiment Page No.

System Diagram i

Solvent/solute systems for use with UOP5 ii

Calibration of the solvent metering pump iii

EXPERIMENT A

Determination of Distribution Coefficient A-1

EXPERIMENT B

Basic Operation of the Liquid/Liquid Extraction Column B-1

EXPERIMENT C

Overall Mass Balance and Mass Transfer Coefficients with theAqueous Phase as the Continuous Medium C-1

EXPERIMENT D

Overall Mass Balance and Mass Transfer with the Organic

Phase as the Continuous Medium D-1

EXPERIMENT E

Demonstration of Solvent Recovery E-1

UOP5 LIQUID/LIQUID EXTRACTION UNIT



Q Q




SOLVENT/SOLUTE SYSTEMS FOR USE WITH UOP5

Two systems are recommended for use with UOP5:

Trichloroethylene, Propionic acid and water

Leksol, Propionic acid and water

Leksol is a non-flammable solvent consisting mainly (approx 95%) of n-propyl

bromide. Leksol is obtainable from Conservation Resources International

(Information available from http://www.conservationresources.com/).




CALIBRATING THE SOLVENT METERING PUMP

Because of tolerances in manufacture and assembly of the solvent metering pump the

flowrate will vary slightly from pump to pump at a given setting of the stroke adjuster.To allow experiments to be conducted at a known flowrate it is recommended that the

following procedure is adopted to obtain a calibration graph for the pump. The graph

obtained can be used in subsequent experiments without the need to repeat the

procedure.

NOTE: The stroke adjustment knob on the metering pump must only be

adjusted when the pump is running. The smaller clamping knob must be

unscrewed before making an adjustment then tightened again when theadjustment knob is in the required position (scale is calibrated 1 – 10).

Set valve V8 to the calibrate position and place a suitable container below the outlet

on valve V8. Start the solvent metering pump then set the stroke adjuster to maximum

flowrate (set F2 to10 on the dial). When the pump and pipework have fully primed

use a measuring cylinder (not supplied) and stopwatch (not supplied) to determine the

actual flowrate in ml/min and record the flowrate obtained at a setting of 10 on the

dial. Change the setting to 9 on the dial. Repeat the procedure to measure and recordthe actual flowrate. Repeat this procedure for settings of 8, 7, 6, 5, 4, 3, 2 & 1 on the

dial.

Plot a graph of flowrate in ml/min against setting of the stroke adjuster (1 -10).

Thereafter any required flowrate may be obtained by using the graph and setting the

stroke adjuster to the appropriate position.




EXPERIMENT A

OBJECT OF EXPERIMENT:

To determine the distribution coefficient for the system organic solvent-Propionic

Acid-Water and to show its dependence on concentration.

EQUIPMENT SET-UP:

The following apparatus is required:

250ml Conical stoppered flask250ml Measuring cylinder

250ml Separating funnel

Pipette with rubber bulb

Sodium Hydroxide Solution (0.1 M)

Phenolphthalein

Propionic acid

WARNING Ensure that diluted Sodium Hydroxide (NaOH) is used whenperforming this experiment.

SUMMARY OF THEORY:

The solvent (water) and solution (organic solvent/propionic acid) are mixed together

and then allowed to separate into the extract phase and the raffinate phase. The extract

phase will be water and propionic acid and the raffinate, organic solvent with a trace

of propionic acid.

The distribution coefficient, K, is defined as the ratio

Concentration of solute in the extract phase, Y

Concentration of solute in the raffinate phase, X

It is assumed that equilibrium exists between the two phases.

At low concentrations, the distribution coefficient is dependent on the concentration

and thus Y = KX.

READINGS TO BE TAKEN:




4. Pour into a separating funnel, leave for 5 minutes and remove the lower

aqueous layer.

5. Take a 10ml sample of this layer and titrate against 0.1 M sodium hydroxide

solution using phenolphthalein as indicator.

6. Repeat the experiment for two further concentrations of propionic acid i.e. for

initial additions of 3ml and 1ml of propionic acid.

RESULTS:

Propionic Acid

added (ml)

Titre of M/10

NaOH

Propionic Acid

Concentration in

Aqueous Layer, Y

Propionic Acid

Concentration in

Organic Layer, X

K=

Y

X

5

3

1




EXPERIMENT B


To observe the hydraulics of counter current flow in a packed column.

EQUIPMENT SET-UP:

The experiment will be carried out using the two immiscible liquids organic solvent

and water and the column will be operated in the following two modes:

(a) The aqueous phase as the continuous medium.(b) The organic phase as the continuous medium.

(a) AQUEOUS PHASE AS CONTINUOUS MEDIUM

(b) ORGANIC PHASE AS CONTINUOUS MEDIUM




SUMMARY OF THEORY:

It is normal to operate a column so that the continuous phase 'wets' the packing. If thepacking is 'wetted' by the dispersed phase then coalescence will be increased and the

mass transfer/unit volume will be reduced. The rate of mass transfer of a solute from

one phase to another is normally increased with greater throughput of material,

because of increased turbulence giving better mixing. There is however, a limit to the

maximum amount of material that can be fed through the column. The limit is called

the 'Flooding Point' and occurs at specific flow rates of constituents resulting in one of

the phases being rejected from the column.

PROCEDURE:





(a) The Aqueous Phase as the Continuous Phase

1. Set the level control (electrode switch S2) to the central (OFF) position.

2. Fill the organic phase feed tank (bottom tank) with 10 litres of

trichloroethylene.

3. Fill the water feed tank with 15 litres of clean de-mineralised water then start

the water feed pump (switch S3) and fill the column with water at a high flowrate.

4. As soon as the water is above the top of the packing, reduce the water flow

rate to 200 ml/min. Start the organic phase metering pump (switch F4) and set

a flow rate of 200 ml/min by adjusting the dial (F2) on the pump (refer to the

calibration graph obtained earlier to determine the required setting on the dial).

Drops of solvent will flow downwards through the packing and collect at the

base of the column.

5. Eventually water will overflow from the top of the column into the water

collection tank (L1). Gradually, the level of the solvent will increase at the

base of the column. When the interface between the solvent and the water is

just above the middle height level electrode, set the level control (electrode




7. Slowly increase both water and organic solvent flow rates in small steps and

note where flooding occurs in the packing.

(b) The Organic Phase as the Continuous Phase

8. Empty the column and return the organic solvent and water into their

respective feed tanks. This is achieved by allowing the weight of the water to

push the organic solvent to the solvent collection tank (top tank L3); this may

mean adding more water with the level control (electrode switch S2) set to the

TOP position. Drain water from the column and tank L1 via the drain valves.

Refill water tank L2.


10. Start the metering pump (switch S4) and fill the column quickly with solvent

at high flowrate. When the solvent reaches the top of the packing reduce the

flow to 200 m1/min by adjusting the dial (F2) on the pump (refer to the


11. Start the water pump (switch S3) and adjust the flow to 200 ml/min. Drops ofwater will flow upwards through the packing and collect on top of the solvent.

12. Gradually, the level of the water will increase on top of the solvent and the

interface between the water and solvent will rise... Eventually water will

overflow from the top of the column into the water collection tank (L1).

13. When the interface between the solvent and the water is just above the middle

height level electrode, set the level control (electrode switch S2) to the TOPposition. The solenoid valve (C3) will open (Red indicator illuminated on the

control panel) and solvent will flow from the base of the column to the top

solvent collection tank (L3).

14. Slowly increase both flow rates in small steps until flooding occurs.

RESULTS:

Observe if there is any difference between operating with the aqueous phase as the

continuous medium compared with the organic phase as the continuous medium.

Is there any difference in droplet size?




EXPERIMENT C


To demonstrate how a mass balance is performed on the extraction column, and to

measure the mass transfer coefficient with the aqueous phase as the continuous

medium.

EQUIPMENT SET-UP:

SUMMARY OF THEORY:

Let Vw = Water flow rate (l/s)

Vo = Organic solvent flow rate (l/s)

X = Propionic Acid concentration in the organic phase (kg/l)

Y = Propionic Acid concentration in the aqueous phase (kg/l)

Subscripts: 1 = Top of column2 = Bottom of column

1. Mass Balance

Propionic Acid extracted from the organic phase (raffinate)




2. Extraction Efficiency

Mass transfer coefficient (based on the raffinate phase)

=Rate of Acid Transfer

Volume of Packing x Mean Driving Force

Log mean driving force =∆x1 − ∆x2

1n ∆x1

∆x 2

where ∆X1 = Driving force at the top of the column = (X2-0)

∆X2 = Driving force at the bottom of the column = (X1-X1*)

where X1* is the concentration in the organic phase which would be in

equilibrium with concentration Y1 in the aqueous phase. The equilibrium

values can be found using the distribution coefficient found in the first

experiment.

PROCEDURE:





1. Add 100ml of propionic acid to 10 litres of the organic phase. Mix well to

ensure an even concentration then fill the organic phase feed tank (bottom

tank) with the mixture.


3. Fill the water feed tank with 15 litres of clean de-mineralised water, start the

water feed pump (switch S3) and fill the column with water at a high flow rate.

4. As soon as the water is above the top of the packing, reduce the flow rate to

200 ml/min. Start the organic phase metering pump (switch F4) and set a flowrate of 200 l/min by adjusting the dial (F2) on the pump (refer to the


Drops of solvent will flow downwards through the packing and collect at the

base of the column.




6. The solenoid valve will open and close at intervals to maintain the interface

between the lowest and middle level electrode.

7. Run for approximately 40 minutes until steady conditions are achieved,

monitor flow rates during this period to ensure that they remain constant.

7. Take 15ml samples from the feed, raffinate and extract streams. DO NOT use

the calibration valve V8 for taking feed samples.

8. Titrate 10ml of each sample against 0.1 M NaOH using phenolphthalein as the

indicator. (To titrate the feed and raffinate they may need continuous stirringusing a magnetic stirrer. Alternatively: 0.025 M NaOH may be used which will

lead to phase inversion of the raffinate and feed streams so that the aqueous

phase is the continuous phase).

WARNING Ensure that diluted Sodium Hydroxide (NaOH) is used when

performing this experiment.

RESULTS:

Flow rate of Aqueous Phase

Flow rate of Organic Phase

Titre of

M/10 NaOH

Concentration of

Propionic Acid kg/l

Feed

Raffinate

Extract

Propionic acid extracted from

the organic phase


the aqueous phase

Mass Transfer Coefficient




EXPERIMENT D


To demonstrate how a mass balance is performed on the extraction column, and to

measure the mass transfer coefficient with the organic phase as the continuous

medium.

EQUIPMENT SET-UP:

ORGANIC PHASE AS CONTINUOUS MEDIUM

SUMMARY OF THEORY:

Let Vw = Water flow rate (l/s)

Vo = Organic phase flow rate (l/s)

X = Propionic Acid concentration in the organic phase (kg/l)

Y = Propionic Acid concentration in the aqueous phase (kg/l)

Subscripts: 1 = Top of column

2 = Bottom of column

1. Mass Balance




2. Extraction Efficiency

Mass transfer coefficient (based on the raffinate phase)

=Rate of Acid Transfer

Volume of Packing x Mean Driving Force

Log mean driving force =∆x1 − ∆x2

1n ∆x1

∆x 2

where ∆X1 = Driving force at the top of the column = (X2-0)∆X2 = Driving force at the bottom of the column = (X1-X1*)

where X1* is the concentration in the organic phase which would be in

equilibrium with concentration Y1 in the aqueous phase. The equilibrium

values can be found using the distribution coefficient found in the first

experiment.

WARNING Ensure that diluted Sodium Hydroxide (NaOH) is used whenperforming this experiment.

PROCEDURE:





1. Add 100ml of propionic acid to 10 litres of the organic solvent. Mix well to

ensure an even concentration then fill the organic phase feed tank (bottom

tank) with the mixture.


3. Fill the water feed tank with 15 litres of clean de-mineralised water.

4. Start the metering pump (switch S4) and fill the column quickly with solvent

at high flowrate. When the solvent reaches the top of the packing reduce the

flow to 200 ml/min by adjusting the dial (F2) on the pump (refer to the

lib i h b i d li d i h i d i h di l)




7. When the interface between the solvent and the water is just above the middle

height level electrode, set the level control (electrode switch S2) to the TOP

position. The solenoid valve (C3) will open (Red indicator illuminated on thecontrol panel) and solvent will flow from the base of the column to the top

solvent collection tank (L3).

6. Run for approximately 40 minutes until steady conditions are obtained,

monitor water flow rate during this period to ensure that it remains constant.

7. Take 15ml samples from the feed, raffinate and extract streams. DO NOT use

the calibration valve V8 for taking feed samples.

8. Titrate 10ml of each sample against M/10 NaOH using phenolphthalein as the

indicator. (To titrate the feed and raffinate they may need continuous stirring

using a magnetic stirrer. Alternatively: 0.025 M NaOH may be used which will

lead to phase inversion of the raffinate and feed streams so that the aqueous

phase is the continuous phase).

RESULTS:

Flow rate of Aqueous Phase

Flow rate of Organic Phase

Titre of

0.1 M NaOH

Concentration of

Propionic Acid kg/l

Feed

Raffinate

Extract


the organic phase


the aqueous phase

Mass Transfer Coefficient




EXPERIMENT E

DEMONSTRATION OF SOLVENT RECOVERY


To recover the solvent used in the liquid/liquid extraction experiments using the

distillation column.

EQUIPMENT SET-UP:

SUMMARY OF THEORY:

In the previous experiments, water has been used as the solvent to extract propionic

acid from the organic solvent. Solvent recovery can now be demonstrated using the

distillation column situated at the rear of the equipment on the left hand side.

The distillation column contains four sieve plates and is equipped with a reflux




PROCEDURE:

On completion of an extraction experiment, organic solvent contaminated with

propionic acid will be contained in the solvent collecting tank. This batch can betransferred using the drain valve at the base of the tank (V7), into the distillation

column. Ensure that the level in the distillation column boiler is at least halfway up

the sight glass on the side of the boiler but do not overfill so that the level rises off the

gauge.

Make sure the regulator R1 is on the minimum setting i.e. fully anti-clockwise and

then press the red switch which will illuminate. Now turn the regulator clockwise to a

setting of say, 7. The cooling water supply to the condenser should now be turned on.

Take a sample of the contaminated organic solvent from the sample valve V10. As in

the experiment to determine the distribution coefficient, take a 10ml sample of this

using a pipette with a rubber bulb and titrate this against 0.1 M sodium hydroxide

solution using phenolphthalein as indicator. (Organic solvent 10ml sample will need

continuous stirring using a magnetic stirrer. Alternatively: 0.025 M NaOH may be

used which will lead to phase inversion of the raffinate and feed streams so that the

aqueous phase is the continuous phase).

When the liquid starts to boil, observe the foaming action on the distillation column

plates and adjust R1 so that a gentle action takes place. Adjust reflux valve C2 so that

not all of the liquid is allowed to fall into the purified solvent tank and some of the

condensed liquid is allowed to reflux back into the column.

At 15 minute intervals, take samples of the liquid in the distillation column boiler

(valve V10) and the purified organic tank from the flexible pipe on the reflux divider.

Do titrations on both samples. Continue to distil until the level of liquid in the boiler

gets low enough to operate the float switch which will turn off the power to the heater.

The purified organic can be transferred from the holding tank into the organic store

tank by using valve V5.

RESULTS:

Sample Titre of NaOH

boiler

Titre of NaOH

holding tank

Conc. acid

boiler

Conc. acid

holding tank

1

2

3

4



GENERAL SAFETY RULES

1 Follow Relevant Instructions

a Before attempting to install, commission or operate equipment, all relevant

suppliers/manufacturers instructions and local regulations should be

understood and implemented.

b It is irresponsible and dangerous to misuse equipment or ignore instructions,

regulations or warnings.

c Do not exceed specified maximum operating conditions (e.g. temperature,

pressure, speed etc.)

2 Installation

a Use lifting tackle where possible to install heavy equipment. Where manual

lifting is necessary beware of strained backs and crushed toes. Get help from

an assistant if necessary. Wear safety shoes where appropriate.

b Extreme care should be exercised to avoid damage to the equipment during

handling and unpacking. When using slings to lift equipment ensure that the

slings are attached to structural framework and do not foul adjacent pipework,

glassware etc. When using fork lift trucks, position the forks beneath structural

framework ensuring that the forks do not foul adjacent pipework, glassware

etc. Damage may go unseen during commissioning creating a potential hazard

to subsequent operators.

c Where special foundations are required follow the instructions provided and

do not improvise. Locate heavy equipment at low level.

d Equipment involving inflammable or corrosive liquids should be sited in a

containment area or bund with a capacity 50% greater than the maximum

equipment contents.

e Ensure that all services are compatible with the equipment and that

independent isolators are always provided and labelled. Use reliable

connections in all instances, do not improvise.

f Ensure that all equipment is reliably earthed and connected to an electrical

supply at the correct voltage. The electrical supply must incorporate a Residual

Current Device (RCD) (alternatively called an Earth Leakage Circuit Breaker -

ELCB) to protect the operator from severe electric shock in the event of

misuse or accident.

g Potential hazards should always be the first consideration when deciding on a

suitable location for equipment. Leave sufficient space between equipment and

between walls and equipment.



3 Commissioning

a Ensure that equipment is commissioned and checked by a competent memberof staff before permitting students to operate it.

4 Operation

a Ensure that students are fully aware of the potential hazards when operating

equipment.

b Students should be supervised by a competent member of staff at all times

when in the laboratory. No one should operate equipment alone. Do not leave

equipment running unattended.

c Do not allow students to derive their own experimental procedures unless they

are competent to do so.

d Serious injury can result from touching apparently stationary equipment when

using a stroboscope to `freeze´ rotary motion.

5 Maintenance

a Badly maintained equipment is a potential hazard. Ensure that a competent

member of staff is responsible for organising maintenance and repairs on a

planned basis.

b Do not permit faulty equipment to be operated. Ensure that repairs are carried

out competently and checked before students are permitted to operate the

equipment.

6 Using Electricity

a At least once each month, check that RCD's (ELCB's) are operating correctly

by pressing the TEST button. The circuit breaker must trip when the button is

pressed (failure to trip means that the operator is not protected and a repair

must be effected by a competent electrician before the equipment or electrical

supply is used).

b Electricity is the commonest cause of accidents in the laboratory. Ensure that

all members of staff and students respect it.

c Ensure that the electrical supply has been disconnected from the equipment

before attempting repairs or adjustments.

d Water and electricity are not compatible and can cause serious injury if they

come into contact. Never operate portable electric appliances adjacent to

equipment involving water unless some form of constraint or barrier is



7 Avoiding fires or explosion

a Ensure that the laboratory is provided with adequate fire extinguishersappropriate to the potential hazards.

b Where inflammable liquids are used, smoking must be forbidden. Notices

should be displayed to enforce this.

c Beware since fine powders or dust can spontaneously ignite under certain

conditions. Empty vessels having contained inflammable liquids can contain

vapour and explode if ignited.

d Bulk quantities of inflammable liquids should be stored outside the laboratory

in accordance with local regulations.

e Storage tanks on equipment should not be overfilled. All spillages should be

immediately cleaned up, carefully disposing of any contaminated cloths etc.

Beware of slippery floors.

f When liquids giving off inflammable vapours are handled in the laboratory,

the area should be ventilated by an ex-proof extraction system. Vents on the

equipment should be connected to the extraction system.

g Students should not be allowed to prepare mixtures for analysis or other

purpose without competent supervision.

8 Handling poisons, corrosive or toxic materials

a Certain liquids essential to the operation of equipment, for example mercury,

are poisonous or can give off poisonous vapours. Wear appropriate protective

clothing when handling such substances. Clean up any spillage immediately

and ventilate areas thoroughly using extraction equipment. Beware of slippery

floors.

b Do not allow food to be brought into or consumed in the laboratory. Never use

chemical beakers as drinking vessels.

c Where poisonous vapours are involved, smoking must be forbidden. Notices

should be displayed to enforce this.

d Poisons and very toxic materials must be kept in a locked cupboard or store

and checked regularly. Use of such substances should be supervised.

e When diluting concentrated acids and alkalis, the acid or alkali should be

added slowly to water while stirring. The reverse should never be attempted.

9 Avoiding cuts and burns

a Take care when handling sharp edged components. Do not exert undue force

on glass or fragile items.



10 Eye protection

a Goggles must be worn whenever there is a risk to the eyes. Risk may arisefrom powders, liquid splashes, vapours or splinters. Beware of debris from fast

moving air streams. Alkaline solutions are particularly dangerous to the eyes.

b Never look directly at a strong source of light such as a laser or Xenon arc

lamp. Ensure that equipment using such a source is positioned so that passers-

by cannot accidentally view the source or reflected ray.

c Facilities for eye irrigation should always be available.

11 Ear protection

a Ear protectors must be worn when operating noisy equipment.

12 Clothing

a Suitable clothing should be worn in the laboratory. Loose garments can cause

serious injury if caught in rotating machinery. Ties, rings on fingers etc. should

be removed in these situations.

b Additional protective clothing should be available for all members of staff and

students as appropriate.

13 Guards and safety devices

a Guards and safety devices are installed on equipment to protect the operator.

The equipment must not be operated with such devices removed.

b Safety valves, cut-outs or other safety devices will have been set to protect the

equipment. Interference with these devices may create a potential hazard.

c It is not possible to guard the operator against all contingencies. Use common

sense at all times when in the laboratory.

d Before starting a rotating machine, make sure staff are aware how to stop it in

an emergency.

e Ensure that speed control devices are always set at zero before starting

equipment.

14 First aid

a If an accident does occur in the laboratory it is essential that first aid

equipment is available and that the supervisor knows how to use it.

b A notice giving details of a proficient first-aider should be prominently

uop5 manual - issue 18

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